I woke up and something felt off. The air was cold. That was normal. At the bottom of the Sea of Corpses, beyond seven thousand meters deep, the temperature never rose above three or four degrees. Even wrapped in a sleeping bag, my breath came out white. But something was definitely off. (What is this feeling...?) Riko pushed herself up with a groan. That's when I noticed. A sound came out. Just an "ah." But that "ah" was clearly different from usual. Low. Raspy. Like a boy's voice. "[surprised]Ah...?" I tried making a sound again. Still low. I held my hand up to my face. My hand was bigger. My fingers were longer. My knuckles were rough and prominent. This wasn't... my hand, was it? But no matter how I looked at it, it was definitely mine. My arm, the part sticking out of my sleeve—all of it was mine. Nervously, I peered into a puddle. At the edge of the rock shelf, in a shallow depression, cold water pooled like a mirror, reflecting my face. "[surprised]Whoa..." I really was a boy. Short black hair. Deep brown eyes. That was still me. But my face was different somehow. My jawline was sharper. I seemed taller. My slender body hadn't changed, but my shoulders were a bit wider. The white shirt and black slacks I'd worn yesterday were still the same, but they hung on me differently now. "[laughing]...I really am a boy." I started laughing. This was crazy. Strange. But before I could feel scared or sad, I just found it funny. That was Riko's bad habit. My body moved before my mind caught up. Curiosity hijacked my emotions. I patted my own face. My cheeks. My jaw. The bridge of my nose. "[excited]My voice is so low. And my hands are huge." I flexed my arm and made a muscle. It was actually there. I didn't have that yesterday. I felt a little proud for a second, then immediately called myself out on it. My heart was still a girl's heart. That much was clear. I remembered yesterday. The three of us—me, Reg, and Nanachi—were exploring the eastern edge of Towa no Hashira. A rocky outcrop we'd nicknamed the Calling Stone Depression, jutting slightly above the water's surface. There was a glowing stone there. About the size of a fist, glowing with a milky white light. When I thought it was pretty and touched it, something jolted through me and I lost consciousness. When I woke up, I was like this. Reg and Nanachi had touched the same stone. All three of us had changed. That stone was the cause. No doubt about it. "[whispers]...Mom would be so surprised if she saw me like this." I whispered it quietly, and my chest ached a little. Lyza. The White Whistle. Riko's mother. She'd gone deep into the Abyss and never came back. What would she say if she saw me now? "My, what a fine Delver you've become," she'd probably say with a laugh. That's what I imagined her being like. I'd barely ever met her, but from the letters and maps she'd left behind, the Lyza I imagined always seemed to be smiling like something was amusing. (But I can change back, right? Probably.) There was no real reason to think that. But I had to believe it, or I couldn't move forward. I walked to the edge of the rock shelf and looked around. The Sea of Corpses was unchanged. This layer, spanning from seven thousand to twelve thousand meters deep, was a freezing underground sea, with crystal pillars sprouting up like weeds. The shortest pillars were two hundred meters tall; the largest exceeded five hundred. Force fields accumulated inside the pillars, scattering a pale blue light, which kept this place in a constant dim glow. There was no sky—just a vague band of light above. Day and night looked about the same. How many days had it taken to descend from Orth to get here? Going down into the Abyss was basically one-way. If you tried to go back up, a curse called "Ascending Burden" would destroy your body. In the Fifth Layer, just trying to go back up would make you lose consciousness, forget who you were, or worst case, your body would transform. So from here on, going back was almost impossible. I'd filed a report with the Tokosha Agency and even written a will before coming here. There was a term for it: "Absolute Descent." Going deeper than the Fifth Layer. Basically a one-way ticket. I'd understood that when I came here. While I was thinking about all that, I heard a splash at my feet. The water surface of the Sea of Corpses below the rock shelf. Dark and deep. Water temperature around two degrees. Visibility below the surface was only about five meters. The force field light barely reached down, and beyond that was pitch black. Something moved in that darkness. At first, I thought a large shadow had just slowly passed beneath the surface. The next instant, the entire rock shelf shook. "[scared]Wh—!" The water surface exploded. What emerged had a jaw three times the size of a human. A Daiou Kabura. A native creature of the Fifth Layer with jaws that could crush entire rock shelves. Its whole body was hidden underwater, invisible. But just the jaw jutting above the surface was more than big enough. It slammed into the rock shelf. Not a "thud"—something much bigger. The impact came from beneath my feet, rocks shattered, and I fell. My supplies went flying. The tent remains fell into the sea. Bags of preserved food scattered. "[scared]This is bad, bad, bad, bad!" My body moved before I could think. I grabbed whatever I could reach from the scattered supplies. A tube with maps. A water skin. A knife. I ran with just those. The rock shelf was crumbling. My footing was disappearing fast. The Daiou Kabura rammed again. This time, the edge of the shelf vanished entirely. If I fell into the sea, I was done. Five minutes in two-degree water and I'd be dead. Transparent jellyfish called Oo-gasumi floated in the water—touching one meant instant death from neurotoxin. Below the surface was a world of death. (The crystal pillar! If I can reach that!) One idea flashed in my mind. The nearest crystal pillar was about five meters away. Reg had told me the pillar's surface was sharp enough to cut your hands if you touched it bare. But if I could climb to the top, the Daiou Kabura couldn't reach me. The problem was whether I could actually climb it. With yesterday's body, I could barely get my fingers to grip the pillar's surface. But now I had a boy's body. (Let's try!) I jumped hard from the edge of the shelf. I tied my supplies to my back, stretched my arms, and hugged the crystal pillar. My hands split open. It hurt. But my fingers caught. I kicked the pillar's surface with my feet, creating friction. I couldn't have done this yesterday. But the finger strength and arm strength of this body were definitely different. "[serious]I can climb it...!" I climbed desperately, inch by inch. My palms split open again and again. Blood came out, staining the pillar's surface red. But I kept climbing. One meter, two meters, three meters. I could hear the Daiou Kabura ramming the rock shelf below. Past five meters, the sound grew distant. "[serious]...Hah, hah..." I caught my breath and looked down. The rock shelf was gone. I could see the Daiou Kabura's back disappearing beneath the water's surface. Huge. Unbelievably huge. One ram from that creature and the entire shelf had vanished. The tent, the fire stand, most of the preserved food—everything had sunk to the bottom of the sea. I stayed clinging to the pillar for a while. "...Reg." I called the name quietly. No answer. "[whispers]...Nanachi." Just silence came back. From five meters up on the crystal pillar, looking out over the Sea of Corpses was wide and quiet and a little scary. Pillars stood like a forest, thin light running between them. My friends had to be somewhere. But I didn't know where. "...We got separated." My voice was low. I noticed it again and found it funny, laughing a little. My palms hurt. More than half the preserved food was gone. Our base was destroyed. We were separated. The situation was pretty much worst-case. But there was no time to feel down. (First, I need to find Reg and Nanachi.) Once I decided that, my mood lifted. That was the kind of person I was. I was better at moving than thinking. I started climbing the crystal pillar slowly. If I got higher, maybe I could spot my friends. My hands hurt, but I was used to it by now. As I climbed, I thought about something. This body isn't so bad, actually. It's easier to climb with. I have more strength. Of course, I don't want to stay like this forever. But right now, in this moment, this form is easier to move in. Thinking that made me feel a little more positive. There had to be a way to change back. If I investigated that glowing stone, I'd figure something out. Besides, when we got back to the shelf yesterday, I'd left the stone there. But now the shelf was gone. Where did that stone go— I looked out into the distance from the top of the pillar. Crystal pillars lined up in the pale blue light. The expanse of the Sea of Corpses. Cool air. Somewhere far off, I heard water moving. (Reg, Nanachi, where are you?) I just hoped they were safe. That was the only thing I really wanted. That's when— Something glowed in the shadow of a pillar. From my position, the angle was wrong to see it clearly. But I definitely caught a glimpse of milky white light. That glowing stone. But I didn't notice. The need to find my friends took priority, and my eyes had already moved elsewhere. In the shadow of a crystal pillar, someone's hand quietly picked up the glowing stone. I didn't know. I moved alone into the Sea of Corpses, unaware.